A certain compound has the following elemental analysis (percent composition by mass), where âXâ is an unknown element (N, O, Cl, or Br):
% C 74.93; % H 12.59; % X 12.48
Its IR spectrum and mass spectrum are given below. Answer the questions on the next page. While you do not need to fully analyze all of this data or determine the exact structure, you may wish to use different spectral details to help determine certain functional groups or other substructures.
a. What element is element X? Explain your reasoning briefly.
b. Calculate the empirical formula of this compound. Remember to
include all your work.
c. Write the mass of the molecular ion (M+ signal of mass spectrum).
d. Calculate the molecular formula of the compound.
e. Write the mass of the base peak as seen on the mass spectrum
f.â What structural fragment(s) were lost from the molecular ion to give the peak whose relative intensity is approximately 70 on the mass spectrum? You may wish to figure out a subset of the molecular formula itself that represents the lost mass, and then figure out some simple alkyl(s) or other group(s) that could give that total formula.
